<!--轮播图基础结构 -->
<template>
  <div class="xtx-carousel" @mouseenter="stop()" @mouseleave="start()">
    <!-- 轮播图容器结构-->
    <ul class="carousel-body">
      <!--要显示的图片加上fade-->
      <li class="carousel-item" v-for="(item,i) in sliders" :key="i" :class="{fade:index===i}">
        <!-- 图片-->
        <RouterLink v-if="item.hrefUrl" :to="item.hrefUrl">
          <img
            :src="item.imgUrl"
            alt="">
        </RouterLink>
        <!--  商品列表-->
        <div v-else class="slider">
          <RouterLink v-for="goods in item" :key="goods.id" :to="`/product/${goods.id}`">
            <img :src="goods.picture" alt="">
            <p class="name ellipsis">{{ goods.name }}</p>
            <p class="price">&yen;{{ goods.price }}</p>
          </RouterLink>
        </div>
      </li>
    </ul>
    <!--上一张-->
    <a @click="toggle(-1)" href="javascript:;" class="carousel-btn prev"><i class="iconfont icon-angle-left"></i></a>
    <!-- 下一张-->
    <a @click="toggle(1)" href="javascript:;" class="carousel-btn next"><i class="iconfont icon-angle-right"></i></a>
    <!-- 指示器-->
    <div class="carousel-indicator">
      <!-- active激活点-->
      <span v-for="(item,i) in sliders" :key="i" :class="{active:index===i}"></span>
    </div>
  </div>
</template>

<script>
import { onUnmounted, ref, watch } from 'vue'

export default {
  name: 'XtxCarousel',
  props: {
    // 轮播图数据
    sliders: {
      type: Array,
      default: () => []
    },
    // 轮播图间隔时间
    duration: {
      type: Number,
      default: 3000
    },
    // 是否自动轮播
    autoPlay: {
      type: Boolean,
      default: false
    }
  },
  setup (props) {
    // 默认显示图片的索引
    const index = ref(0)
    // 轮播图自动播放的逻辑
    let timer = null
    const autoPlayFn = () => {
      // 防止定时器重复
      clearInterval(timer)
      // 自动播放，每隔多久切换索引
      timer = setInterval(() => {
        index.value++
        if (index.value >= props.sliders.length) {
          index.value = 0
        }
      }, props.duration)
    }

    // 1. 监听Slider数据变化，如果有数且autoPlay是true
    watch(() => props.sliders, (newVal) => {
      // 有数据&开启自动播放，才调用自动播放函数
      if (newVal.length && props.autoPlay) {
        index.value = 0
        autoPlayFn()
      }
    }, { immediate: true })

    // 2.鼠标进入离开，移出开启自动，前提条件autoPlay为true
    const stop = () => {
      if (timer) clearInterval(timer)
    }
    const start = () => {
      if (props.sliders.length && props.autoPlay) {
        autoPlayFn()
      }
    }
    // 3.点击点点跨域且华北，上一张下一张
    const toggle = (step) => {
      const newIndex = index.value + step
      // 超出的情况,太大了
      if (newIndex >= props.sliders.length) {
        index.value = 0
        return
      }
      // 超出的情况,太小了
      if (newIndex < 0) {
        index.value = props.sliders.length - 1
        return
      }
      // 正常
      index.value = newIndex
    }

    // 4. 组件卸载，清除定时器
    onUnmounted(() => {
      clearInterval(timer)
    })
    return {
      index,
      stop,
      start,
      toggle
    }
  }
}
</script>

<style scoped lang="less">
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;

  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }

    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;

      &.fade {
        opacity: 1;
        z-index: 1;
      }

      img {
        width: 100%;
        height: 100%;
      }
    }

    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;

      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;

        ~ span {
          margin-left: 12px;
        }

        &.active {
          background: #fff;
        }
      }
    }

    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, .2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;

      &.prev {
        left: 20px;
      }

      &.next {
        right: 20px;
      }
    }
  }

  // 轮播商品
  .slider {
    display: flex;
    justify-content: space-around;
    padding: 0 40px;

    > a {
      width: 240px;
      text-align: center;

      img {
        padding: 20px;
        width: 230px !important;
        height: 230px !important;
      }

      .name {
        font-size: 16px;
        color: #666;
        padding: 0 40px;
      }

      .price {
        font-size: 16px;
        color: @priceColor;
        margin-top: 15px;
      }
    }
  }

  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }

}
</style>
